Texas is still recovering from Harvey, a Category 4 storm that dumped 60 inches of rain over parts of the state. Researchers are already trying to determine the likelihood of a comparable disaster happening again.

A report published in the Proceedings of the National Academy of Sciences says that storms that hit Texas with more than 20 inches of rain are six times more likely now than they were at the end of the 20th century, when the chance of such a hurricane hitting Texas in a given...